Effect of oral antigen administration on nasal blockage in experimental allergic rhinitis in guinea pigs

Objective and design: We evaluated the effectiveness of oral treatment with Japanese cedar pollen on experimental allergic rhinitis in guinea pigs. Subjects: Male Hartley guinea pigs. Treatment: From 16 days before the first sensitisation, 1 and 100 mg/time/animal pollen suspension was orally administered twice weekly. Animals were then sensitised and repeatedly challenged with the pollen. Method: Guinea pigs were sensitised by intranasal instillation of cedar pollen extracts adsorbed onto Al(OH), at a dose of 0.3 mug pollen protein/0.3 mg Al(OH)(3)/3 mul/nostril twice a day for 7 days. Then the animal was challenged by inhalation with cedar pollen (1.8 mg/nostril) once every week. We evaluated the effects of the oral treatment with antigen on: 1) sneezing frequency, 2) nasal blockage after antigen challenge, 3) nasal hyperresponsiveness to histamine and leukotriene DO and 4) titres of anaphylactic antibodies. Results: During the course of the high dose administration, several animals died from a possible cytotoxicity, whereas the low dose caused no discernible change. The oral administration of the pollen at both the doses significantly inhibited nasal blockage, and the hyperresponsiveness to the stimuli was also strongly suppressed by the oral treatment. Inhibitory effectiveness did not differ substantially between the 1 and 100 mg/animal-treated groups. In contrast, neither sneezing frequency nor the increasing level of anaphylactic antibodies was influenced by the oral administration. Conclusions: In this study, we found that the pollen-induced nasal blockage and hyperresponsiveness were suppressed by the oral administration of the pollen in the sensitised guinea pig.